1. Field of the Invention
The present invention relates to an apparatus and a method for manufacturing a wavelength conversion laser light source device.
2. Description of the Related Art
A wavelength conversion laser light source device is a light source (light source device) that is constituted by aligning a laser device that includes either an LD module or a solid laser or both of these elements and a wavelength converting device at a specific position. In such a light source device, a laser beam emitted from the laser device is incident onto the optical waveguide of the wavelength converting device (a second harmonic wave generation device, or an “SHG device”, which emits a laser beam having a half the wavelength of the incident light, is adopted here) to generate high-power green light and blue light sources. The light source device resonates and amplifies the incident light inside the optical waveguide, and thereby generates and outputs a second harmonic having a half the wavelength of the incident light.
Optical connection establishing methods by which light emitted from the laser device is gathered onto the optical waveguide of the SHG device (by adjusting the position of the optical axis between the two optical devices) include passive alignment and active alignment. With the passive alignment, the positions of the optical devices are determined by performing image processing with reference to the outer shapes or target marks of the optical devices, or the adjustment positions are determined mechanically from the mutual engagement of the components. With the active alignment, a laser beam is incident onto the optical waveguide that is optically connected to the laser device, and the amount of the laser light output through the optical waveguide is measured by a power meter or the like. Thereafter, while measuring an amount of the output laser light, the laser device or the optical waveguide is three-dimensionally moved to find its optimal position at which the amount of laser light reaches the maximum value. Among such optical axis adjusting methods, the optimal method is selected in accordance with conditions such as the positioning accuracy of the optical devices included in the light source and a target optical output. After the optical axis is adjusted, the laser device and the SHG device are adhered to each other at the adjusted position with an adhesive or the like.
For example, according to the optical axis adjusting method suggested in Japanese Patent Application Laid-open No. 1-180507, optical fibers are moved in two directions orthogonal to the optical axis, in two planes orthogonal to each other that include the optical axis, and in two directions perpendicular to the optical axis direction, while monitoring the light passing through the optical fibers, in such a manner as to maximize the amount of light. A highly efficient optical connection can thereby be achieved between the semiconductor module and the optical fibers.
With the optical device adjusting method described in Japanese Patent Application Laid-open No. 2004-109256, the maximum value of the amount of light in the direction of the optical axis can be obtained from the values that periodically vary with changes of intervals between the optical devices, and by using the thus obtained maximum value, the optical axis is adjusted at a point where the amount of light reaches its maximum which is obtained in a state in which there is no reflection on the edge faces. BY this adjustment, the influence of interference of light reflected between the optical devices is eliminated.
When the optical axis is adjusted while monitoring the optical output as suggested in the above conventional technologies, however, unevenness in waveforms of the laser light may be observed when checked with an actual drive current actually flowing the adhered laser device. This occurs from a subtle positional displacement between the laser device and the SHG device that cannot be observed in the output fluctuation. For example, the laser outputs of the same level may come out with different drive waveforms. The conventional technologies have a problem of fluctuations in response characteristics of laser light when the drive waveform of the laser light varies for each laser light (when the variation of the waveform is large).